1. Field
Aspects of embodiments of the present invention relate to a polarizing plate and a liquid crystal display including the same.
2. Description of the Related Art
Polarizing plates are disposed inside and outside a liquid crystal cell for the purpose of controlling an oscillation direction of light to visualize display patterns of a liquid crystal display. Although the liquid crystal display was applied to small apparatuses in the initial stages of development, recently, the liquid crystal display is used in a wide range of applications including notebook computers, liquid crystal monitors, liquid crystal color projectors, liquid crystal televisions, navigation systems for vehicles, personal phones, indoor and outdoor measurement instruments, and the like.
A polarizing plate used in a liquid crystal display includes a polarizer and protective films formed on one or both sides of the polarizer. The primary function of the protective films is to protect the polarizer. A protective film stacked on one side of the polarizer is stretched to have a viewing angle compensation function through suitable phase retardation, whereas a protective film stacked on the other side of the polarizer is formed of a triacetylcellulose (TAC) film, considering that phase retardation does not influence optical characteristics. However, the TAC film is typically produced through volatilization of a solvent by a casting process and is thus more expensive than general polymer films in the art.
Accordingly, inexpensive polymer films including a polyethylene terephthalate (PET) film have been developed in order to replace the TAC film. However, such an inexpensive polymer film is fabricated through high magnification stretching in order to improve yield and thus has high retardation. A liquid crystal display fabricated by stacking such an ultrahigh-retardation film is likely to suffer from rainbow spots causing deterioration in image quality.
In addition, the TAC film has a polar group and thus does not require a bi-adhesive primer. However, a polymer film such as a PET film has a non-polar surface and thus requires the bi-adhesive primer and exhibits lower transmittance than the TAC film. Moreover, when bonded to a polarizer, the PET film has a problem of compromise between bonding performance and transmittance. That is, good bonding performance of the PET film to the polarizer can lead to deterioration in transmittance, or vice versa. In order to solve this problem, an Index of refraction and thickness of the bi-adhesive primer with respect to a base film become important.
In the related art, Korean Patent Publication No. 10-2011-0024442 A discloses a polymer base including a highly functional primer layer exhibiting good bonding performance and an optical member using the same.